1. Technical Field
The present invention relates to a robot hand, a robot, and a holding mechanism.
2. Related Art
There are two known robot hand holding systems for holding a target object using a plurality of fingers: holding the target by rotation of the roots of the fingers (for example, JP-A-2010-201538), and holding the target by a parallel shift of the fingers (for example, JP-A-5-220687).
According to the method which rotates the roots of the fingers, the contact angle of the fingers for contact with the target change according to the size of the target to be held, in which case the shape and force of the fingers need to change for each of the targets. Accordingly, this method requires complicated structure and control of the robot hand. Concerning this point, however, the method which conducts a parallel shift of the fingers does not vary the contact angle of the fingers for contact with the target, and thus can simplify the structure and control of the robot hand.
Despite of this advantage, the method of conducting a parallel shift of the fingers has a limitation in that the method is difficult to use for holding a small target. This limitation is imposed for the following reasons. In general, holding a small target takes place in a narrow working space. For example, in the case of picking up small parts and assembling the parts to predetermined positions, the parts to be assembled are often arranged within a small space with only small clearances between one another. In this case, there is generally only a limited space therebetween for receiving the robot hand for picking up the parts. Moreover, for the attachment of the picked-up parts, the parts often need to be assembled in a small space in accordance with the small size of the parts. On the other hand, the robot hand of the type conducting a parallel shift of the fingers has large components for supporting the movable fingers, therefore the robot hand has an increased size and thus is difficult to use for working in a narrow working space.